Add qc_get_preparable_stmt

This function will return the preparable statement of a PREPARE
statement as a COM_QUERY GWBUF. That is, once obtained, the normal
query classifier functions can be used for obtaining information
about the preparable statement itself.

include/maxscale/query_classifier.h

@@ -342,6 +342,23 @@ typedef struct query_classifier
      *         exhaustion or equivalent.
      */
     int32_t (*qc_get_function_info)(GWBUF* stmt, const QC_FUNCTION_INFO** infos, uint32_t* n_infos);
+
+    /**
+     * Return the preparable statement of a PREPARE statement.
+     *
+     * @param stmt             A statement.
+     * @param preparable_stmt  On return, the preparable statement (provided @c stmt is a
+     *                         PREPARE statement), if @c QC_RESULT_OK is returned. Otherwise
+     *                         NULL.
+     *
+     * @attention The returned GWBUF is the property of @c stmt and will be deleted when
+     *            @c stmt is. If the preparable statement need to be retained beyond the
+     *            lifetime of @c stmt, it must be cloned.
+     *
+     * @return QC_RESULT_OK, if the parsing was not aborted due to resource
+     *         exhaustion or equivalent.
+     */
+    int32_t (*qc_get_preparable_stmt)(GWBUF* stmt, GWBUF** preparable_stmt);
 } QUERY_CLASSIFIER;
 
 /**
@@ -578,6 +595,22 @@ char* qc_get_prepare_name(GWBUF* stmt);
  */
 qc_query_op_t qc_get_prepare_operation(GWBUF* stmt);
 
+/**
+ * Returns the preparable statement of a PREPARE statment. Other query classifier
+ * functions can then be used on the returned statement to find out information
+ * about the preparable statement. The returned @c GWBUF should not be used for
+ * anything else but for obtaining information about the preparable statement.
+ *
+ * @param stmt  A buffer containing a COM_QUERY packet.
+ *
+ * @return The preparable statement, if @stmt was a PREPARE statement, or
+ *         NULL.
+ *
+ * @attention The returned @c GWBUF is the property of @c stmt and will be
+ *            deleted along with it.
+ */
+GWBUF* qc_get_preparable_stmt(GWBUF* stmt);
+
 /**
  * Returns the tables accessed by the statement.
  *

query_classifier/qc_dummy/qc_dummy.cc

@@ -96,7 +96,7 @@ int32_t qc_dummy_setup(const char* args)
     return QC_RESULT_OK;
 }
 
-int qc_dummy_process_init(void)
+int32_t qc_dummy_process_init(void)
 {
     return QC_RESULT_OK;
 }
@@ -105,7 +105,7 @@ void qc_dummy_process_end(void)
 {
 }
 
-int qc_dummy_thread_init(void)
+int32_t qc_dummy_thread_init(void)
 {
     return QC_RESULT_OK;
 }
@@ -114,6 +114,12 @@ void qc_dummy_thread_end(void)
 {
 }
 
+int32_t qc_dummy_get_preparable_stmt(GWBUF* stmt, GWBUF** preparable_stmt)
+{
+    *preparable_stmt = NULL;
+    return QC_RESULT_OK;
+}
+
 extern "C"
 {
     MXS_MODULE* MXS_CREATE_MODULE()
@@ -138,6 +144,7 @@ extern "C"
             qc_dummy_get_prepare_operation,
             qc_dummy_get_field_info,
             qc_dummy_get_function_info,
+            qc_dummy_get_preparable_stmt,
         };
 
         static MXS_MODULE info =

query_classifier/qc_mysqlembedded/qc_mysqlembedded.cc

@@ -1851,6 +1851,15 @@ int32_t qc_mysql_get_prepare_operation(GWBUF* stmt, int32_t* operation)
     return QC_RESULT_OK;
 }
 
+int32_t qc_mysql_get_preparable_stmt(GWBUF* stmt, GWBUF** preparable_stmt)
+{
+    *preparable_stmt = NULL;
+
+    // TODO: Extract preparable stmt.
+    ss_dassert(!true);
+    return QC_RESULT_OK;
+}
+
 static bool should_exclude(const char* name, List<Item>* excludep)
 {
     bool exclude = false;

query_classifier/qc_sqlite/qc_sqlite.c

@@ -2796,6 +2796,7 @@ static int32_t qc_sqlite_get_table_names(GWBUF* query, int32_t fullnames, char**
 static int32_t qc_sqlite_get_canonical(GWBUF* query, char** canonical);
 static int32_t qc_sqlite_query_has_clause(GWBUF* query, int32_t* has_clause);
 static int32_t qc_sqlite_get_database_names(GWBUF* query, char*** names, int* sizep);
+static int32_t qc_sqlite_get_preparable_stmt(GWBUF* stmt, GWBUF** preparable_stmt);
 
 static bool get_key_and_value(char* arg, const char** pkey, const char** pvalue)
 {
@@ -3411,6 +3412,38 @@ int32_t qc_sqlite_get_function_info(GWBUF* query, const QC_FUNCTION_INFO** infos
     return rv;
 }
 
+int32_t qc_sqlite_get_preparable_stmt(GWBUF* stmt, GWBUF** preparable_stmt)
+{
+    QC_TRACE();
+    int32_t rv = QC_RESULT_ERROR;
+    ss_dassert(this_unit.initialized);
+    ss_dassert(this_thread.initialized);
+
+    *preparable_stmt = NULL;
+
+    QC_SQLITE_INFO* info = get_query_info(stmt);
+
+    if (info)
+    {
+        if (qc_info_is_valid(info->status))
+        {
+            // TODO: Extract the preparable stmt.
+            ss_dassert(!true);
+            rv = QC_RESULT_OK;
+        }
+        else if (MXS_LOG_PRIORITY_IS_ENABLED(LOG_INFO))
+        {
+            log_invalid_data(stmt, "cannot report field info");
+        }
+    }
+    else
+    {
+        MXS_ERROR("The query could not be parsed. Response not valid.");
+    }
+
+    return rv;
+}
+
 /**
  * EXPORTS
  */
@@ -3437,6 +3470,7 @@ MXS_MODULE* MXS_CREATE_MODULE()
         qc_sqlite_get_prepare_operation,
         qc_sqlite_get_field_info,
         qc_sqlite_get_function_info,
+        qc_sqlite_get_preparable_stmt,
     };
 
     static MXS_MODULE info =

server/core/query_classifier.c

@@ -283,6 +283,18 @@ char* qc_get_prepare_name(GWBUF* query)
     return name;
 }
 
+GWBUF* qc_get_preparable_stmt(GWBUF* stmt)
+{
+    QC_TRACE();
+    ss_dassert(classifier);
+
+    GWBUF* preparable_stmt = NULL;
+
+    classifier->qc_get_preparable_stmt(stmt, &preparable_stmt);
+
+    return preparable_stmt;
+}
+
 struct type_name_info field_usage_to_type_name_info(qc_field_usage_t usage)
 {
     struct type_name_info info;